This is a proposal for the renewal of a multi-categorical General Clinical Research Center at the Children's and University Hospitals. Major areas of research include: 1. Pediatric Liver Disease. Studies are defining the pathophysiology and treatment of new inborn errors of bile acid metabolism and peroxisomal disorders and the pathogenesis of bone disease and growth failure in cholestatic liver disease. 2. Bone Health. Studies will examine the effect of maternal age during lactation on bone demineralization and the value of progestins in ameliorating the loss. Studies will evaluate the role of calcium supplementation on bone accretion in prepubertal children, the role of exercise in bone accretion in preschoolers and the pathogenesis and management of bone disease in juvenile rheumatoid arthritis. 3. Cancer. Using resources available through a proposed Tissue Procurement Facility supported by the GCRC, basic science and clinical investigators will obtain tumors for investigations of the cell biology and molecular mechanisms of malignancies. Studies will investigate thyroid cancer, neural tumors, breast cancer, and the APC and Bloom's Syndrome genes. 4. Gaucher Disease. Despite the availability of enzyme research for Gaucher Disease, disability from bone disease persists. Studies will evaluate the potential value of bisphosphonates as an adjunct to enzyme replacement for the treatment of bone disease in Gaucher Disease. 5. Cystic Fibrosis. Studies are defining the safety of a replication-deficient recombinant adenovirus construct to deliver the CF transmembrane conductance gene to the nasal epithelium. 6. Cholesterol Synthesis. Studies are evaluating the potential effect of the cholesterol content in breast milk or infant formulae and cholesterol synthesis rates to determine if early exposure to cholesterol in the human infant may have an "imprinting" effect on cholesterol synthesis.